Transformer winding and a method of reinforcing a transformer winding

Abstract

A transformer winding having a conductor wound in a plurality of turns is disclosed, wherein the transformer winding includes a reinforcing part arranged at a winding transition in a manner so that the reinforcing part covers more than 180 degrees of the conductor circumference, whereby the bending strength of the conductor at the location of the reinforcing part is increased. The resistibility of the transformer winding against bending stress is hence improved.

What is claimed is: 
     
       1. A transformer winding having a conductor wound in a plurality of turns, the transformer winding comprising
 a reinforcing part arranged at a winding transition of the conductor in a manner so that the reinforcing part covers more than 180 degrees of the conductor circumference, whereby the bending strength of the conductor at the location of the winding transition is increased. 
 
     
     
       2. The transformer winding according to  claim 1 , wherein the main component of the reinforcing part is a fibre reinforced polymer. 
     
     
       3. The transformer winding according to  claim 1 , wherein the reinforcing part increases the bending strength of the conductor by at least 25% at the location of the winding transition. 
     
     
       4. The transformer winding according to  claim 1 , wherein
 the reinforcing part extends, in the axial direction of the conductor, a distance corresponding to less than a circumference of a winding turn. 
 
     
     
       5. The transformer winding according to  claim 1 , wherein the transformer winding comprises a plurality of radial duct spacers spaced at a duct spacer distance along the circumferential direction of the winding, and wherein the reinforcing part extends, in the axial direction of the conductor, a distance corresponding to 1-4 duct spacer distances. 
     
     
       6. The transformer winding according to  claim 1 , wherein
 the reinforcing part includes a component providing semi-conducting properties to the reinforcing part so that electrical shielding of the reinforcing part is achieved. 
 
     
     
       7. The transformer winding according to  claim 1 , wherein the conductor is a continuously transposed cable conductor. 
     
     
       8. A transformer including the transformer winding according to  claim 1 . 
     
     
       9. The transformer according to  claim 8 , wherein the transformer winding forms an inner winding of the transformer. 
     
     
       10. The transformer according to  claim 8 , wherein the transformer winding forms a low voltage winding of the transformer. 
     
     
       11. The transformer according to  claim 8 , wherein the transformer is a power transformer designed to have an electrical power rating of 25 MVA or higher. 
     
     
       12. A method of increasing the bending strength of a transformer winding having a conductor, wherein reinforcing fibres in a thermosetting polymer are arranged at a winding transition in a manner so that the reinforcing fibres form a reinforcing part extending around more than 180 degrees of the circumference of the conductor at least part of the winding transition. 
     
     
       13. The method according to  claim 12 , wherein
 the step of arranging comprises arranging reinforcing fibres which have been pre-impregnated with a thermosetting polymer at the winding transition to form said reinforcing part. 
 
     
     
       14. The method according to  claim 12 , wherein
 the thermosetting polymer comprises a semi-conducting component arranged to provide electrical shielding to the reinforcing part. 
 
     
     
       15. The method according to  claim 12 , wherein
 curing of the reinforcing part is performed upon hot drying of the transformer winding, or of a transformer of which the transformer winding forms a part.